Lavatory unit

ABSTRACT

A lavatory unit ( 10 ) comprising a tank body ( 12 ) connected to a pressurised water supply ( 20 ), and flushing means ( 14, 21, 23 ) for releasing water from the tank body via an outlet to a lavatory bowl ( 11 ). The flushing means includes an elastic bladder ( 21 ) the interior of which is in communication with the tank, the tank being generally sealed otherwise, such that the bladder stressed with the expansion of air forced from the tank as the tank fills with water and the bladder relaxes elastically as the tank empties, and thereby assists in ejecting the water under pressure from the tank to provide a better flushing action.

This invention relates to lavatory or WC tanks.

In a conventional lavatory a tank is mounted above a bowl having aU-bend trap and a flush mechanism is used to release water from the bowlunder gravity and thereby clean waste solids or liquids from the bowl.

Typically, in order to properly flush the bowl, significant quantitiesof water are required—for example 7-10 litres per flush. This leads tovery high water consumption levels and correspondingly high sewagetreatment requirements.

The present invention aims to provide an improved lavatory tank havingsignificantly lower water consumption requirements without any decreasein efficiency.

The invention provides a lavatory tank comprising a tank body, means forconnecting the tank body to a pressurised liquid supply, and means forreleasing liquid from the tank body via an outlet, wherein saidreleasing means includes an elastic means which becomes stressed as thetank fills with liquid and which becomes relaxed as the tank empties.

The stored energy in the elastic means provides a higher water velocityfrom the tank outlet, which in turn enables a lower volume of water toachieve the same flushing efficiency as is achieved from a conventionaltank (which releases water under gravity).

Preferably, the elastic means comprises an expandable-contractiblemember the interior of which is in communication with defining aninternal space which is in communication with the interior of the tank,whereby as liquid fills the tank it displaces gas from the empty tank toexpand said internal space.

In preferred embodiments, the elastic means is an air-filled bladderconnected to a sealed water tank. In such embodiments the air located inthe water tank (when empty) is forced by the pressure of the incomingwater into the internal space defined by the bladder. Thus, the tankinterior and bladder interior form a closed system connected to theexterior by a release or flush valve and connected also to thepressurised water supply.

The invention also provides a lavatory unit comprising a lavatory tankas described herein and a lavatory bowl connected to the tank via thetank outlet.

Preferably, the bowl comprises a substantially cylindrical sectionadapted to hold a volume of water is normal use and a flared sectionextending from a narrow diameter portion, defined by the top of thecylindrical section, to a wide diameter portion, defined by the mouth ofthe bowl, the water level being maintained in normal use in thecylindrical section at least 5 cm below the flared section.

Suitably the cylindrical section leads to a U-shaped trap. When the bowlis flushed with water emerging from the tank at high velocity, watertends to fill the cylindrical section more quickly than the trap canempty, thereby building up a head of water which helps remove solidsfrom the trap as it empties.

The invention will now be further illustrated by the followingdescription of an embodiment thereof, given by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 is a side sectional elevation of a lavatory unit according to theinvention;

FIG. 2 is a front sectional elevation of a detail of the lavatory unitof FIG. 1, shown after flushing; and

FIG. 3 is a front sectional elevation of a detail of the lavatory unitof FIG. 1, shown before flushing

In FIG. 1 there is indicated, generally at 10, a lavatory unit accordingto the invention, comprising a bowl 11 connected to a water tank 12 by aflush pipe 13 having a flush valve 14 (described in greater detailbelow).

Bowl 11 comprises a flared section 15 and a cylindrical section 16 abovea conventional U-bend trap 17. The water level 18 in the trap 17 lies atleast 5 cm below the top 19 of the cylindrical section, (preferably atleast 7.5 cm).

FIG. 2 shows the water tank 12 in greater detail. Tank 12 is fed by afeed pipe 20 connected to a pressurised water supply such as a domesticcold water tank or a water mains (which is suitably pressurecontrolled). The interior is also in communication with an air bladder21 mounted in a support housing 22 above the tank 12. Support housing 22is open to the atmosphere allowing bladder 21 to freely expand andcontract.

The tank 12 and bladder 21 are shown at the end of flushing: the tank 12is empty, i.e. air-filled, and the flush valve 14 is open having allowedthe water originally held in tank 12 to escape via the flush pipe 13.

Flush valve 14 is a ball valve which controls the flow through bothflush pipe 13 and feed pipe 20; when flush pipe 14 is open, feed pipe 20is closed and vice versa.

A handle 23 (FIG. 1) controls the position of valve 14, and aspring-loaded means (not shown) biases the handle 23, and thus the valve14, to the position shown in FIG. 3, wherein the flush pipe 13 is closedand the feed pipe 20 is open, allowing the tank 12 to refill.

FIG. 3 shows the tank 12 at equilibrium, filled with water 24. The entryof water 24 under pressure has displaced the air within the tank 12 intobladder 21 which is elastically expanded. Accordingly, when flush valve14 is actuated, the stored energy of the pressurised air in the bladder21 is released to force the water 24 through the flush pipe 13. In thisway, the velocity of flushing water is greatly increased relative toconventional systems which rely on gravity only to release water to thebowl.

Because of the increased velocity of flush water, aided by the bowldesign (discussed further below), a greatly reduced volume of water canaccomplish satisfactory flushing. In tests it has been found that tanksaccording to the invention containing between 2 and 2.5 litres willaccomplish the same flushing action as a conventional tank of from 7 to10 litres.

The bladder can be of an elastic strength chosen to meet the local waterpressure and can, for example, be concertina-shaped or elasticallyexpandable (as shown). Other suitable elastic means may also be used.

Referring back to FIG. 1, it can be seen that whereas a conventionalbowl has an internal overhang around the rim from under which the flushwater emerges, the bowl 11 of the illustrated embodiment has a simplerim 26. Water emerges from the mouth 25 of flush pipe 13 at a sufficientvelocity to completely cleanse the interior 27 of bowl 11.

The shape and dimensions of the bowl 11 and the angle and diameter ofthe flush pipe 13 are chosen to ensure complete cleansing of the bowl'sinterior 27 without water splashing over the rim 26.

For example, a bowl having the dimensions indicated below (see FIG. 1)was found to be optimally flushed with a flush pipe entering at a=100°:

b = 15 cm c = 8 cm d = 15 cm e = 35° f = 37° g = 3 cmThese dimensions are interrelated, and the angle a will also depend onthe resilience of the bladder 21, and hence the water velocity.

When flush water enters the bowl, it tends to build up above water level18 before the pressure of this head of water causes the water in eitherside of the U-bend to equalise. This action assists in more thoroughflushing of the bowl and can be attributed to the bowl shape whereby thelength of cylindrical section 16 above water level 18 generates agreater head of pressure than in a conventional bowl having a largerwater surface area.

In an alternative embodiment of bowl, a trap-door is located at the endof cylindrical section 16, allowing the waste in the toilet bowl to beflushed directly into the sewer pipe without a U-bend. In thisembodiment, a venting pipe is provided in the sewer pipe below andadjacent to the trap door, to allow noxious odours to escape from thesewer pipe. The trap door is suitably activated by a linkage extendingfrom the flush handle 23.

1. A lavatory tank comprising a tank body, means for connecting the tankbody to a pressurised liquid supply, and means for releasing liquid fromthe tank body via an outlet, wherein said releasing means comprises anelastic means which becomes stressed as the tank fills with liquid andwhich becomes relaxed as the tank empties.
 2. A lavatory tank accordingto claim 1, wherein said elastic means comprises anexpandable-contractible member defining an internal space which is incommunication with the interior of the tank, whereby as liquid fills thetank it displaces gas from the empty tank to expand the said internalspace.
 3. A lavatory tank according to claim 2, wherein saidexpandable-contractible member is chosen from one of the following: aflexible elastic bladder, a concertina-like flexible member.
 4. Alavatory tank according to claim 2, wherein said expandable-contractiblemember is mounted within a support housing, said support housingdefining an internal chamber, said internal chamber defining the maximumexpansion of said expandable-contractible member.
 5. A lavatory tankaccording to claim 4, wherein at least one aperture is defined on saidsupport housing, said at least one aperture extending from said internalchamber of said support housing to the exterior of said support housing.6. A lavatory tank according to claim 1, wherein said lavatory tankfurther comprises a four way ball valve, said means for connecting thetank body to a pressurised liquid supply coupled to said ball valve,said releasing means further coupled to said ball valve.
 7. A lavatorytank according to claim 1, wherein said releasing means furthercomprises a sluice valve coupled to said outlet.
 8. A lavatory unitcomprising a tank according to claim 1, and a lavatory bowl connected tothe tank via the tank outlet.
 9. A lavatory unit according to claim 8,wherein the bowl comprises a substantially cylindrical section and aflared section, said cylindrical section adapted to hold a volume ofwater in normal use, said flared section extending from a narrowdiameter portion, defined by the top of the cylindrical section, to awide diameter portion, defined by the mouth of the bowl.
 10. A lavatoryunit according to claim 9, wherein the water level is maintained innormal use in the cylindrical section at least 5 cm below the flaredsection.
 11. A lavatory unit according to claim 9, wherein saidcylindrical section is coupled to a U-bend trap.
 12. A lavatory unitaccording to claim 9, wherein said lavatory unit further comprises atrap-door, said cylindrical section coupled to said trap door.
 13. Alavatory unit according to claim 9, wherein the ratio of the height ofsaid cylindrical section to the height of said flared section is between4:3 to 5:3, wherein the angle of incline of said flared section isbetween 30°-40°, and wherein said tank outlet enters into the flaredsection of said bowl at an angle of between 5°-15°.
 14. A lavatory unitaccording to claim 13, wherein the height of said cylindrical section isapproximately 23 cm, wherein the height of said flared section isapproximately 15 cm, wherein the tank outlet comprises a tube having adiameter of approximately 3 cm, the angle of entry of said tube intosaid flared section approximately 10°, and wherein the angle of inclineof said flared section varies from 37° at that portion of the flaredsection immediately adjacent the point of entry of said tube into theflared section to 35° at that portion of the flared section directlyopposite the point of entry of said tube into the flared section.